IN THIS CHAPTER
Crossing the road to get to the other side: Parallel lines and transversals
Tracing the family tree of quadrilaterals
Plumbing the depths of parallelograms, rectangles, and rhombuses
Proving a figure is a parallelogram or other special quadrilateral
In Chapters 4 and 5, you deal with three-sided polygons: triangles. In this chapter, you check out quadrilaterals, polygons with four sides. Then, in Chapter 7, you see polygons up to a gazillion sides. Totally exciting, right?
Parallel Line Properties
Most of the quadrilaterals you’ll deal with have parallel sides, so let’s begin with some info on parallel lines.
Parallel lines with a transversal
Check out Figure 6-1, which shows three lines that kind of resemble a giant not-equal sign. The two horizontal lines are parallel, and the third line that crosses them is called a transversal. As you can see, the three lines form eight angles.